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Only a small fraction of the global ridge system (~65000 km) and of the vast continental margin regions have been explored and their communities described. It is the aim of ChEss to improve the knowledge on the diversity, abundance and distribution of species from vents, seeps and other reducing habitats at a global scale, understanding the abiotic and biotic processes that shape and maintain these ecosystems and their biogeography.
Main ChEss Science Questions
* I. What are the species' relationships between different habitats: vents, seeps, whale falls, sunken wood and OMZs?
* II. What is the role of deep-water circulation and geographical barriers in gene flow and biogeography?
* III. What are the factors driving patterns of biodiversity in these habitats?
Objective 1. To create a centralised database
To create a centralised database, [https://web.archive.org/web/20090523105231/http://www.noc.soton.ac.uk/chess/database/db_home.php ChEssBase], of deep-water vent, cold seep, whalefall and OMZ species. ChEssBase is a web-based database that incorporates archived and newly collected biological material. The database is geo- and bio-referenced. ChEssBase is available online and has been integrated with OBIS.
Objective 2. To develop a long-term field programme
To develop a long-term [https://web.archive.org/web/20090523110542/http://www.noc.soton.ac.uk/chess/science/sci_field.php field programme] to locate potential vent and seep sites and continue research on whalefalls and OMZ sites. The field programme aims to explain the main gaps in our knowledge of the diversity, abundance and distribution of chemosynthetic species globally. A limited number of target areas have been selected where specific scientific questions relevant to biogeographical issues will be answered.
The target areas have been grouped into two categories. Category I, combined areas: Area A: Equatorial Atlantic Belt region; Area B: the SE Pacific region; Area C: NZ region; Area D: the Arctic and Antarctic regions, within the International Polar Year. Category II, specific areas: 1 – The ice-covered Gakkel Ridge, 2 – the (ultra)-slow ridges of the Norwegian-Greenland Sea, 3 – the northern MAR between the Iceland and Azores hot-spots; 4 – the Brazilian continental margin, 5 – the East Scotia Ridge and Bransfield Strait, 6 – the SW Indian Ridge, 7 – the Central Indian Ridge.
During the field programme, ChEss will promote the development and refinement of deep-towed, remotely operated (ROV) and autonomous underwater (AUV) vehicle technologies to locate, map and sample new chemosynthetic systems. Using optical, chemical and acoustic techniques, ChEss researchers hope to gain a better understanding of not only biogeographical patterns, but to determine the processes driving these ecosystems.
During the field programme, ChEss will promote the development and refinement of deep-towed, remotely operated (ROV) and autonomous underwater (AUV) vehicle technologies to locate, map and sample new chemosynthetic systems. Using optical, chemical and acoustic techniques, ChEss researchers hope to gain a better understanding of not only biogeographical patterns, but to determine the processes driving these ecosystems.
Objective 3: Outreach and Education
ChEss has multi-lingual [https://web.archive.org/web/20081204112716/http://www.noc.soton.ac.uk/chess/education/edu_home.php education pages] related to vents, seeps and whalefalls. There is a dedicated page for key outreach initiatives such as live cruise diaries, open days, schools activities etc.
ChEss has joined forces with the other deep-sea CoML projects and this has resulted in the creation of the DEep-Sea Education and Outreach group (DESEO) that has produced a book "Deeper than Light" published in 5 languages. | 0 | Theoretical and Fundamental Chemistry |
In chemistry, a dynamic equilibrium exists once a reversible reaction occurs. Substances transition between the reactants and products at equal rates, meaning there is no net change. Reactants and products are formed at such a rate that the concentration of neither changes. It is a particular example of a system in a steady state.
In physics, concerning thermodynamics, a closed system is in thermodynamic equilibrium when reactions occur at such rates that the composition of the mixture does not change with time. Reactions do in fact occur, sometimes vigorously, but to such an extent that changes in composition cannot be observed. Equilibrium constants can be expressed in terms of the rate constants for reversible reactions. | 0 | Theoretical and Fundamental Chemistry |
The carbonate pump, sometimes called the carbonate counter pump, starts with marine organisms at the ocean's surface producing particulate inorganic carbon (PIC) in the form of calcium carbonate (calcite or aragonite, CaCO). This CaCO is what forms hard body parts like shells. The formation of these shells increases atmospheric CO due to the production of CaCO in the following reaction with simplified stoichiometry:Coccolithophores, a nearly ubiquitous group of phytoplankton that produce shells of calcium carbonate, are the dominant contributors to the carbonate pump. Due to their abundance, coccolithophores have significant implications on carbonate chemistry, in the surface waters they inhabit and in the ocean below: they provide a large mechanism for the downward transport of CaCO. The air-sea CO flux induced by a marine biological community can be determined by the rain ratio - the proportion of carbon from calcium carbonate compared to that from organic carbon in particulate matter sinking to the ocean floor, (PIC/POC). The carbonate pump acts as a negative feedback on CO taken into the ocean by the solubility pump. It occurs with lesser magnitude than the solubility pump. | 0 | Theoretical and Fundamental Chemistry |
Sodium dodecyl sulfate (SDS) or sodium lauryl sulfate (SLS), sometimes written sodium laurilsulfate, is an organic compound with the formula and structure . It is an anionic surfactant used in many cleaning and hygiene products. This compound is the sodium salt of the 12-carbon organosulfate. Its hydrocarbon tail combined with a polar "headgroup" give the compound amphiphilic properties that make it useful as a detergent. SDS is also component of mixtures produced from inexpensive coconut and palm oils. SDS is a common component of many domestic cleaning, personal hygiene and cosmetic, pharmaceutical, and food products, as well as of industrial and commercial cleaning and product formulations. | 1 | Applied and Interdisciplinary Chemistry |
Reversible solid oxide cells (rSOCs), as solid oxide fuel cells, are made of four main components: the electrolyte, the fuel and oxygen electrodes, and the interconnects.
The electrodes are porous layers that favor the reactants diffusion inside their structure and catalyze electrochemical reactions. In the single technologies like SOFCs and SOECs, the electrodes serve a single purpose, hence they are called with their specific names. The anode is where the oxidation reaction occurs, while the cathode is where the reduction reaction takes place. In reversible solid oxide cells, on the other hand, both modalities can occur alternatively in the same device. For this reason, the generic names of fuel electrode and oxygen electrode are preferred instead. On the fuel electrode the reactions involving the fuel oxidation (SOFC modality) or the reduction of the products to produce the fuel (SOEC modality) takes place. On the oxygen electrode, oxygen reduction (SOFC modality) or oxygen ions oxidation to form oxygen gas (SOEC modality) takes place.
State-of-the-art materials for rSOCs are those used for SOFCs. The most common fuel electrodes are made by a mixture of nickel, that serves as electronic conductor, and yttria-stabilized zirconia (YSZ), a ceramic material characterized by high conductivity to oxygen ions at elevated temperature. The most popular oxygen electrode materials are lanthanum strontium cobalt ferrite (LSCF) and lanthanum strontium chromite (LSC), perovskite materials able to catalyze oxygen reduction and oxide ion oxidation reactions.
The electrolyte is a solid-state layer placed between the two electrodes. It is an electric insulator, it is impermeable to gas flow but permeable to oxygen ions flow. Hence, the main properties of this component are the high ion conductivity and the low electrical conductivity. When the rSOC is operated in SOFC mode, oxygen ions flow from the oxygen electrode to the fuel electrode, where the fuel oxidation occurs. In SOEC mode, the reactants are reduced in the anode with the production of oxygen ions, which flow towards the oxygen electrode. The most widespread material for electrolytes is YSZ.
The interconnects are usually made of metallic materials. They provide or collect the electrons involved in the electrochemical reactions. In addition, they are shaped internally with gas channels to distribute the reactants over the cell surface. | 0 | Theoretical and Fundamental Chemistry |
RNAs are a type of large biological molecules, whose individual building blocks are called nucleotides. The name poly(A) tail (for polyadenylic acid tail) reflects the way RNA nucleotides are abbreviated, with a letter for the base the nucleotide contains (A for adenine, C for cytosine, G for guanine and U for uracil). RNAs are produced (transcribed) from a DNA template. By convention, RNA sequences are written in a 5′ to 3′ direction. The 5′ end is the part of the RNA molecule that is transcribed first, and the 3′ end is transcribed last. The 3′ end is also where the poly(A) tail is found on polyadenylated RNAs.
Messenger RNA (mRNA) is RNA that has a coding region that acts as a template for protein synthesis (translation). The rest of the mRNA, the untranslated regions, tune how active the mRNA is. There are also many RNAs that are not translated, called non-coding RNAs. Like the untranslated regions, many of these non-coding RNAs have regulatory roles. | 1 | Applied and Interdisciplinary Chemistry |
Sample preparation of the OPV is of the utmost importance when performing pc-AFM studies. The sampling substrate is recommended to be conductive, as well as transparent, to the light source which is irradiated upon it. Numerous studies have used ITO-coated glass as their conductive substrate. Because of high cost of ITO, however, there have been attempts to utilize other semiconducting layers, such as zinc oxide (ZnO) and carbon nanotubes as an alternative to ITO. Although these semiconductors are relatively inexpensive, high quality ITO layers are still being used extensively for PV applications. Poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate), more commonly known as PEDOT:PSS, is a transparent, polymeric conductive layer which is usually placed between the ITO and the active OPV layer. The PEDOT:PSS is a conductive polymer is stable over various applied charges. In most studies, PEDOT:PSS is spin-coated onto the ITO-coated glass substrates directly after plasma cleaning of the ITO. Plasma cleaning, as well as halo-acid etching, have been shown to improve the surface uniformity and conductivity of the substrate. This PEDOT:PSS layer is then annealed to the ITO prior to spin-coating the OPV layer onto the substrate. Studies by Pingree et al. have shown the direct correlation between annealing time and both peak and average photocurrent generation. Once this OPV film is spin-coated onto the substrate, it is then annealed at temperatures between 70 and 170 °C, for periods up to an hour depending on the procedure as well as OPV being used. | 0 | Theoretical and Fundamental Chemistry |
Printing materials must fit a broad spectrum of criteria, one of the foremost being biocompatibility. The resulting scaffolds formed by 3D printed materials should be physically and chemically appropriate for cell proliferation. Biodegradability is another important factor, and insures that the artificially formed structure can be broken down upon successful transplantation, to be replaced by a completely natural cellular structure. Due to the nature of 3D printing, materials used must be customizable and adaptable, being suited to wide array of cell types and structural conformations. | 1 | Applied and Interdisciplinary Chemistry |
Often, modification of the structure will take place around the glycosidic linkage. Replacement of one or other of the glycosidic oxygen atoms by carbon, sulfur, nitrogen etc. will alter the properties of the glycosidic bond. The molecules produced in this way would be called carbasugars or C-glycosides, thiosugars or thioglycosides, or iminosugars or glycosylamines.
When nitrogen is introduced, the glycomimetic may become positively charged at physiological pH, meaning that it may act as an enzyme inhibitor, either by Coulombic interaction with carboxylate amino acid side-chains in the enzyme active site, or by mimicking positive-charge build-up at the transition state of the reaction, or both. Iminosugars (sometimes referred to erroneously as azasugars) are classic examples of molecules with this behaviour. Glycosylamines typically have a lower stability, being easily hydrolysed, which means that to exploit an exocyclic nitrogen substituent at C-1, further modification is necessary. An example of this would be the additional substitution of the ring-oxygen for carbon as is seen in valienamine.
Altering the structure of a carbohydrate will normally result in several changes to the properties of the molecule. As well as changing the stability of the glycosidic bond, the ring-conformation may be affected. Also the conformation of the glycosidic bond may be affected. As well as obvious changes in the immediate vicinity of the substitution, e.g. that replacement of an acetal oxygen by methylene (CH2) would result in loss of a hydrogen-bond participatory atom, such a substitution is expected to have more subtle effects resulting from a change in the dipole of the molecule, such as slight changes in hydrogen bonding or pKa values of the unchanged hydroxyl groups. Substitution by CF2 rather than methylene has been explored in efforts to address this and come up with better mimetics while still retaining the hydrolytic stability gained by the modification. | 1 | Applied and Interdisciplinary Chemistry |
The primary conditions for soil development are controlled by the chemical composition of the rock on which the soil will be. Rock types that form the base of the soil profile are often either sedimentary (carbonate or siliceous), igneous or metaigneous (metamorphosed igneous rocks) or volcanic and metavolcanic rocks. The rock type and the processes that lead to its exposure at the surface are controlled by the regional geologic setting of the specific area under study, which revolve around the underlying theory of plate tectonics, subsequent deformation, uplift, subsidence and deposition.
Metaigneous and metavolcanic rocks form the largest component of cratons and are high in silica. Igneous and volcanic rocks are also high in silica, but with non-metamorphosed rock, weathering becomes faster and the mobilization of ions is more widespread. Rocks high in silica produce silicic acid as a weathering product. There are few rock types that lead to localized enrichment of some of the biologically limiting elements like phosphorus (P) and nitrogen (N). Phosphatic shale (O) and phosphorite (> 15% PO) form in anoxic deep water basins that preserve organic material. Greenstone (metabasalt), phyllite, and schist release up to 30–50% of the nitrogen pool. Thick successions of carbonate rocks are often deposited on craton margins during sea level rise. The widespread dissolution of carbonate and evaporites leads to elevated levels of Mg, , Sr, Na, Cl and ions in aqueous solution. | 0 | Theoretical and Fundamental Chemistry |
Many beam HREM images of extremely thin samples are only directly interpretable in terms of a projected crystal structure if they have been recorded under special conditions, i.e. the so-called Scherzer defocus. In that case the positions of the atom columns appear as black blobs in the image (when the spherical aberration coefficient of the objective lens is positive - as always the case for uncorrected TEMs). Difficulties for interpretation of HREM images arise for other defocus values because the transfer properties of the objective lens alter the image contrast as function of the defocus. Hence atom columns which appear at one defocus value as dark blobs can turn into white blobs at a different defocus and vice versa. In addition to the objective lens defocus (which can easily be changed by the TEM operator), the thickness of the crystal under investigation has also a significant influence on the image contrast. These two factors often mix and yield HREM images which cannot be straightforwardly interpreted as a projected structure. If the structure is unknown, so that image simulation techniques cannot be applied beforehand, image interpretation is even more complicated. Nowadays two approaches are available to overcome this problem: one method is the exit-wave function reconstruction method, which requires several HREM images from the same area at different defocus and the other method is crystallographic image processing (CIP) which processes only a single HREM image. Exit-wave function reconstruction provides an amplitude and phase image of the (effective) projected crystal potential over the whole field of view. The thereby reconstructed crystal potential is corrected for aberration and delocalisation and also not affected by possible transfer gaps since several images with different defocus are processed. CIP on the other side considers only one image and applies corrections on the averaged image amplitudes and phases. The result of the latter is a pseudo-potential map of one projected unit cell. The result can be further improved by crystal tilt compensation and search for the most likely projected symmetry. In conclusion one can say that the exit-wave function reconstruction method has most advantages for determining the (aperiodic) atomic structure of defects and small clusters and CIP is the method of choice if the periodic structure is in focus of the investigation or when defocus series of HREM images cannot be obtained, e.g. due to beam damage of the sample. However, a recent study on the catalyst related material Cs[NbWO] shows the advantages when both methods are linked in one study. | 0 | Theoretical and Fundamental Chemistry |
Alguronic acid is the tradename created for an undetermined mix of polysaccharides produced by microalgae clogging filters in algae cultures. The tradename has been coined by Solazyme. The indeterminate mix of chemicals is claimed to function to protect the microalgae, and has been processed and formulated in a range of products. In 2011, the acid was introduced to the market as an active ingredient in a commercial product called [http://www.algenist.com/ Algenist] anti-aging skincare formulas.
Alguronic acid is not a technical name referring to a single polysaccharide, but a mix of algae extracts claimed to have anti-aging benefits for the skin. | 0 | Theoretical and Fundamental Chemistry |
In organic chemistry, a carbyne is a general term for any compound whose structure consists of an electrically neutral carbon atom connected by a single covalent bond and has three non-bonded electrons. The carbon atom has either one or three unpaired electrons, depending on its excitation state; making it a radical. The chemical formula can be written or (also written as ), or just CH.
Carbynes can be seen as derivatives of the simplest such compound, the methylidyne radical or unsubstituted carbyne or , in which the functional group is a hydrogen atom.
Reported for the first time back in 1967 by Kasatochkin, carbyne is an infinite sp1 hybridized long linear chain of carbon, where each link is just a single carbon atom. | 0 | Theoretical and Fundamental Chemistry |
This work also explains why genomes such as the human genome have billions of bases, and why only a small fraction (~2%) codes for proteins and other regulatory elements. If split genes originated from random primordial DNA sequences, they would contain a significant amount of DNA that represented by introns. Furthermore, a genome assembled from random DNA containing split genes would also include intergenic random DNA. Thus, genomes that originated from random DNA sequences had to be large, regardless of the complexity of the organism.
The observation that several organisms such as the onion (~16 billion bases) and salamander (~32 billion bases) have much larger genomes than humans (~3 billion bases) while the organisms are no more complex than humans comports with the theory. Furthermore, the fact that several organisms with smaller genomes have a similar number of genes as human, such as C. elegans (genome size ~100 million bases, ~19,000 genes) and Arabidopsis thaliana (genome size ~125 million bases, ~25,000 genes), supports the theory. The theory predicts that the introns in the split genes in these genomes could be the “reduced” (or deleted) form compared to larger genes with long introns, thus leading to reduced genomes. In fact, researchers have recently proposed that these smaller genomes are actually reduced genomes. | 1 | Applied and Interdisciplinary Chemistry |
* A nuclease frees the nucleotide
** A nucleotidase creates adenosine, then adenosine deaminase creates inosine
** Alternatively, AMP deaminase creates inosinic acid, then a nucleotidase creates inosine
* Purine nucleoside phosphorylase acts upon inosine to create hypoxanthine
* Xanthine oxidase catalyzes the biotransformation of hypoxanthine to xanthine
* Xanthine oxidase acts upon xanthine to create uric acid | 1 | Applied and Interdisciplinary Chemistry |
Due to the exceptional porosity of COFs, they have been used extensively in the storage and separation of gases such as hydrogen, methane, etc. | 0 | Theoretical and Fundamental Chemistry |
Elvucitabine is a deoxycytidine analogue with activity against HIV resistant to several other nucleoside analogues, including zidovudine and lamivudine. This is partly because of high intracellular levels of its triphosphate metabolite reached in cells. Clinical trials of elvucitabine are on hold, because it has shown bone marrow suppression in some patients, with CD4+ cell numbers dropping as early as two days after initiation of dosing. | 1 | Applied and Interdisciplinary Chemistry |
Plastic pipes used in manufacturing.
Plastic pipe fittings include PVC pipe fittings, PP / PPH pipe fitting mould, PE pipe and ABS pipe fitting. | 1 | Applied and Interdisciplinary Chemistry |
A reaction step of a chemical reaction is defined as: "An elementary reaction, constituting one of the stages of a stepwise reaction in which a reaction intermediate (or, for the first step, the reactants) is converted into the next reaction intermediate (or, for the last step, the products) in the sequence of intermediates between reactants and products". To put it simply, it is an elementary reaction which goes from one reaction intermediate to another or to the final product. | 0 | Theoretical and Fundamental Chemistry |
Nucleosome Remodeling Factor (NURF) is an ATP-dependent chromatin remodeling complex first discovered in Drosophila melanogaster (fruit fly) that catalyzes nucleosome sliding in order to regulate gene transcription. It contains an ISWI ATPase, making it part of the ISWI family of chromatin remodeling complexes. NURF is highly conserved among eukaryotes and is involved in transcriptional regulation of developmental genes. | 1 | Applied and Interdisciplinary Chemistry |
Researchers from the company Colossal confirmed that their primary goal when trying to revive the woolly mammoth is to better the environment and climate change itself. | 1 | Applied and Interdisciplinary Chemistry |
Some of the benefits of BNAs include ideal for the detection of short RNA and DNA targets; increase the thermal stability of duplexes; capable of single nucleotide discrimination; increases the thermal stability of triplexes; resistance to exo- and endonucleases resulting in a high stability for in vivo and in vitro applications; increased target specificity; facilitate Tm normalization; strand invasion enables detection of "hard to access" samples; compatible with standard enzymatic processes. | 1 | Applied and Interdisciplinary Chemistry |
Clay minerals can be incorporated in lime-metakaolin mortars to improve mechanical properties. Electrochemical separation helps to obtain modified saponite-containing products with high smectite-group minerals concentrations, lower mineral particles size, more compact structure, and greater surface area. These characteristics open possibilities for the manufacture of high-quality ceramics and heavy-metal sorbents from saponite-containing products.
Furthermore, tail grinding occurs during the preparation of the raw material for ceramics; this waste reprocessing is of high importance for the use of clay pulp as a neutralizing agent, as fine particles are required for the reaction. Experiments on the histosol deacidification with the alkaline clay slurry demonstrated that neutralization with the average pH level of 7.1 is reached at 30% of the pulp added and an experimental site with perennial grasses proved the efficacy of the technique. Moreover, the reclamation of disturbed lands is an integral part of the social and environmental responsibility of the mining company and this scenario addresses the community necessities at both local and regional levels. | 0 | Theoretical and Fundamental Chemistry |
Deep-sea hydrothermal vents, emitting hot acidic or alkaline water, would have created external proton gradients. These provided energy that primordial organisms could have exploited. To keep the flows separate, such an organism could have wedged itself in the rock of the hydrothermal vent, exposed to the hydrothermal flow on one side and the more alkaline water on the other. As long as the organism's membrane (or passive ion channels within it) is permeable to protons, the mechanism can function without ion pumps. Such a proto-organism could then have evolved further mechanisms such as ion pumps and ATP synthase. | 1 | Applied and Interdisciplinary Chemistry |
The biocompatibility of surgically implanted foreign biomaterial refers to the interactions between the biomaterial and the host body tissue. Cell line as well as cell type such as fibroblasts can largely impact tissue responses towards implanted foreign devices by changing cell morphology. Thus the cell source as well as protein adsorption, which is dependent on biomaterial surface property, play a crucial role in tissue response and cell infiltration at the scaffold site. | 1 | Applied and Interdisciplinary Chemistry |
For example, photo-fermentation with Rhodobacter sphaeroides SH2C can be employed to convert small molecular fatty acids into hydrogen.
Enterobacter aerogenes is an outstanding hydrogen producer. It is an anaerobic facultative and mesophilic bacterium that is able to consume different sugars and in contrast to cultivation of strict anaerobes, no special operation is required to remove all oxygen from the fermenter. E. aerogenes has a short doubling time and high hydrogen productivity and evolution rate. Furthermore, hydrogen production by this bacterium is not inhibited at high hydrogen partial pressures; however, its yield is lower compared to strict anaerobes like Clostridia. A theoretical maximum of 4 mol H/mol glucose can be produced by strict anaerobic bacteria. Facultative anaerobic bacteria such as E. aerogenes have a theoretical maximum yield of 2 mol H/mol glucose. | 1 | Applied and Interdisciplinary Chemistry |
Example of devices that can be used to measure this ratio are the CHN analyzer and the continuous-flow isotope ratio mass spectrometer (CF-IRMS). However, for more practical applications, desired C/N ratios can be achieved by blending common used substrates of known C/N content, which are readily available and easy to use. | 0 | Theoretical and Fundamental Chemistry |
Cell biology (also cellular biology or cytology) is a branch of biology that studies the structure, function, and behavior of cells. All living organisms are made of cells. A cell is the basic unit of life that is responsible for the living and functioning of organisms. Cell biology is the study of the structural and functional units of cells. Cell biology encompasses both prokaryotic and eukaryotic cells and has many subtopics which may include the study of cell metabolism, cell communication, cell cycle, biochemistry, and cell composition. The study of cells is performed using several microscopy techniques, cell culture, and cell fractionation. These have allowed for and are currently being used for discoveries and research pertaining to how cells function, ultimately giving insight into understanding larger organisms. Knowing the components of cells and how cells work is fundamental to all biological sciences while also being essential for research in biomedical fields such as cancer, and other diseases. Research in cell biology is interconnected to other fields such as genetics, molecular genetics, molecular biology, medical microbiology, immunology, and cytochemistry. | 1 | Applied and Interdisciplinary Chemistry |
MOZ (Monocytic Leukemia Zinc Finger Protein), Ybf2/Sas3, Sas2 and Tip60 (Tat Interacting Protein) all make up MYST, another well known family that exhibits acetylating capabilities. This family includes Sas3, essential SAS-related acetyltransferase (Esa1), Sas2, Tip60, MOF, MOZ, MORF, and HBO1. The members of this family have multiple functions, not only with activating and silencing genes, but also affect development and have implications in human diseases. Sas2 and Sas3 are involved in transcription silencing, MOZ and TIF2 are involved with the formation of leukemic transclocation products while MOF is involved in dosage compensation in Drosophila. MOF also influences spermatogenesis in mice as it is involved in the expansion of H2AX phosphorylation during the leptotene to pachytene stages of meiosis. HAT domains for this family are approximately 250 residues which include cysteine-rich, zinc binding domains as well as N-terminal chromodomains. The MYST proteins Esa1, Sas2 and Sas3 are found in yeast, MOF is found in Drosophila and mice while Tip60, MOZ, MORF, and HBO1 are found in humans. Tip60 has roles in the regulation of gene transcription, HBO has been found to impact the DNA replication process, MORF is able to acetylate free histones (especially H3 and H4) as well as nucleosomal histones. | 0 | Theoretical and Fundamental Chemistry |
Loosely speaking, the existence or construction of a periodic table of elements creates an ordering of the elements, and so they can be numbered in order.
Dmitri Mendeleev said that he arranged his first periodic tables (first published on March 6, 1869) in order of atomic weight ("Atomgewicht"). However, in consideration of the elements observed chemical properties, he changed the order slightly and placed tellurium (atomic weight 127.6) ahead of iodine (atomic weight 126.9). This placement is consistent with the modern practice of ordering the elements by proton number, Z', but that number was not known or suspected at the time.
A simple numbering based on periodic table position was never entirely satisfactory. In addition to the case of iodine and tellurium, several other pairs of elements (such as argon and potassium, cobalt and nickel) were later shown to have nearly identical or reversed atomic weights, thus requiring their placement in the periodic table to be determined by their chemical properties. However the gradual identification of more and more chemically similar lanthanide elements, whose atomic number was not obvious, led to inconsistency and uncertainty in the periodic numbering of elements at least from lutetium (element 71) onward (hafnium was not known at this time). | 0 | Theoretical and Fundamental Chemistry |
The U.S. Institute of Medicine (IOM) updated Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for magnesium in 1997. If there is not sufficient information to establish EARs and RDAs, an estimate designated Adequate Intake (AI) is used instead. The current EARs for magnesium for women and men ages 31 and up are 265 mg/day and 350 mg/day, respectively. The RDAs are 320 and 420 mg/day. RDAs are higher than EARs so as to identify amounts that will cover people with higher than average requirements. RDA for pregnancy is 350 to 400 mg/day depending on age of the woman. RDA for lactation ranges 310 to 360 mg/day for same reason. For children ages 1–13 years the RDA increases with age from 65 to 200 mg/day. As for safety, the IOM also sets Tolerable upper intake levels (ULs) for vitamins and minerals when evidence is sufficient. In the case of magnesium the UL is set at 350 mg/day. The UL is specific to magnesium consumed as a dietary supplement, the reason being that too much magnesium consumed at one time can cause diarrhea. The UL does not apply to food-sourced magnesium. Collectively the EARs, RDAs and ULs are referred to as Dietary Reference Intakes.
= Adequate intake
The European Food Safety Authority (EFSA) refers to the collective set of information as Dietary Reference Values, with Population Reference Intake (PRI) instead of RDA, and Average Requirement instead of EAR. AI and UL defined the same as in United States. For women and men ages 18 and older the AIs are set at 300 and 350 mg/day, respectively. AIs for pregnancy and lactation are also 300 mg/day. For children ages 1–17 years the AIs increase with age from 170 to 250 mg/day. These AIs are lower than the U.S. RDAs. The European Food Safety Authority reviewed the same safety question and set its UL at 250 mg/day - lower than the U.S. value. The magnesium UL is unique in that it is lower than some of the RDAs. It applies to intake from a pharmacological agent or dietary supplement only, and does not include intake from food and water. | 1 | Applied and Interdisciplinary Chemistry |
George Church has compiled a list of potential genetic modifications based on scientific studies for possibly advantageous traits such as less need for sleep, cognition-related changes that protect against Alzheimer's disease, disease resistances, higher lean muscle mass and enhanced learning abilities along with some of the associated studies and potential negative effects. | 1 | Applied and Interdisciplinary Chemistry |
Genetic diversity is often lost within captive populations due to the founder effect and subsequent small population sizes. Minimizing the loss of genetic diversity within the captive population is an important component of ex situ conservation and is critical for successful reintroductions and the long term success of the species, since more diverse populations have higher adaptive potential. The loss of genetic diversity due to the founder effect can be minimized by ensuring that the founder population is large enough and genetically representative of the wild population. This is often difficult because removing large numbers of individuals from the wild populations may further reduce the genetic diversity of a species that is already of conservation concern. An alternative to this is collecting sperm from wild individuals and using this via artificial insemination to bring in fresh genetic material. Maximizing the captive population size and the effective population size can decrease the loss of genetic diversity by minimizing the random loss of alleles due to genetic drift. Minimizing the number of generations in captivity is another effective method for reducing the loss of genetic diversity in captive populations. | 1 | Applied and Interdisciplinary Chemistry |
Neptunium diarsenide forms crystals of the tetragonal system, space group P4/nmm, cell parameters a = 0.3958 nm, c = 0.8098 nm. | 0 | Theoretical and Fundamental Chemistry |
Transition metal oxides are compounds composed of oxygen atoms bound to transition metals. They are commonly utilized for their catalytic activity and semiconducting properties. Transition metal oxides are also frequently used as pigments in paints and plastics, most notably titanium dioxide. Transition metal oxides have a wide variety of surface structures which affect the surface energy of these compounds and influence their chemical properties. The relative acidity and basicity of the atoms present on the surface of metal oxides are also affected by the coordination of the metal cation and oxygen anion, which alter the catalytic properties of these compounds. For this reason, structural defects in transition metal oxides greatly influence their catalytic properties. The acidic and basic sites on the surface of metal oxides are commonly characterized via infrared spectroscopy, calorimetry among other techniques. Transition metal oxides can also undergo photo-assisted adsorption and desorption that alter their electrical conductivity. One of the more researched properties of these compounds is their response to electromagnetic radiation, which makes them useful catalysts for redox reactions, isotope exchange and specialized surfaces. | 0 | Theoretical and Fundamental Chemistry |
A new formula describing size effect was proposed. This formula has a form
where is the nanoparticle radius and is wave number. It is supposed here that the time dependence of the electromagnetic field is given by the factor In this paper Bruggemans approach was used, but electromagnetic field for electric-dipole oscillation mode inside the picked particle was computed without applying quasi-static approximation. Thus the function is due to the field nonuniformity inside the picked particle. In quasi-static region (, i.e. for Ag this function becomes constant and formula (5) becomes identical with Bruggemans formula. | 0 | Theoretical and Fundamental Chemistry |
Copper concentrates produced by mines are sold to smelters and refiners who treat the ore and refine the copper and charge for this service via treatment charges (TCs) and refining charges (RCs). The TCs are charged in US$ per tonne of concentrate treated and RCs are charged in cents per pound treated, denominated in US dollars, with benchmark prices set annually by major Japanese smelters. The customer in this case can be a smelter, who on-sells blister copper ingots to a refiner, or a smelter-refiner which is vertically integrated.
One prevalent form of copper concentrate contains gold and silver, like the one produced by Bougainville Copper Limited from the Panguna mine from the early 1970s to the late 1980s.
The typical contract for a miner is denominated against the London Metal Exchange price, minus the TC-RCs and any applicable penalties or credits. Penalties may be assessed against copper concentrates according to the level of deleterious elements such as arsenic, bismuth, lead or tungsten. Because a large portion of copper sulfide ore bodies contain silver or gold in appreciable amounts, a credit can be paid to the miner for these metals if their concentration within the concentrate is above a certain amount. Usually the refiner or smelter charges the miner a fee based on the concentration; a typical contract will specify that a credit is due for every ounce of the metal in the concentrate above a certain concentration; below that, if it is recovered, the smelter will keep the metal and sell it to defray costs.
Copper concentrate is traded either via spot contracts or under long term contracts as an intermediate product in its own right. Often the smelter sells the copper metal itself on behalf of the miner. The miner is paid the price at the time that the smelter-refiner makes the sale, not at the price on the date of delivery of the concentrate. Under a Quotational Pricing system, the price is agreed to be at a fixed date in the future, typically 90 days from time of delivery to the smelter.
A-grade copper cathode is of 99.99% copper in sheets that are 1 cm thick, and approximately 1 meter square weighing approximately 200 pounds. It is a true commodity, deliverable to and tradeable upon the metal exchanges in New York City (COMEX), London (London Metals Exchange) and Shanghai (Shanghai Futures Exchange). Often copper cathode is traded upon the exchanges indirectly via warrants, options, or swap contracts such that the majority of copper is traded upon the LME/COMEX/SFE, but delivery is achieved directly, logistically moving the physical copper, and transferring the copper sheet from the physical warehouses themselves.
The chemical specification for electrolytic grade copper is ASTM B 115-00 (a standard that specifies the purity and maximum electrical resistivity of the product). | 1 | Applied and Interdisciplinary Chemistry |
Molecular biomarkers have been defined as biomarkers that can be discovered using basic and acceptable platforms such as genomics and proteomics. Many genomic and proteomics techniques are available for biomarker discovery and a few techniques that are recently being used can be found on that page. Apart from genomics and proteomics platforms biomarker assay techniques, metabolomics, lipidomics, glycomics, and secretomics are the most commonly used as techniques in identification of biomarkers. | 1 | Applied and Interdisciplinary Chemistry |
The Journal of Photochemistry and Photobiology C: Photochemistry Reviews is abstracted and indexed in BIOSIS Previews, Chemistry & Chemical Engineering, Chemistry Citation Index, Current Contents/Physical, Chemical & Earth Sciences, Science Citation Index and Scopus. According to the Journal Citation Reports, the journal has a 2014 impact factor of 16.094. | 0 | Theoretical and Fundamental Chemistry |
Explanation of diauxie depended on the characterization of additional mutations affecting the lac genes other than those explained by the classical model. Two other genes, cya and crp, subsequently were identified that mapped far from lac, and that, when mutated, result in a decreased level of expression in the presence of IPTG and even in strains of the bacterium lacking the repressor or operator. The discovery of cAMP in E. coli led to the demonstration that mutants defective the cya gene but not the crp gene could be restored to full activity by the addition of cAMP to the medium.
The cya gene encodes adenylate cyclase, which produces cAMP. In a cya mutant, the absence of cAMP makes the expression of the lacZYA genes more than ten times lower than normal. Addition of cAMP corrects the low Lac expression characteristic of cya mutants. The second gene, crp, encodes a protein called catabolite activator protein (CAP) or cAMP receptor protein (CRP).
However the lactose metabolism enzymes are made in small quantities in the presence of both glucose and lactose (sometimes called leaky expression) due to the fact that the RNAP can still sometimes bind and initiate transcription even in the absence of CAP. Leaky expression is necessary in order to allow for metabolism of some lactose after the glucose source is expended, but before lac expression is fully activated.
In summary:
* When lactose is absent then there is very little Lac enzyme production (the operator has Lac repressor bound to it).
* When lactose is present but a preferred carbon source (like glucose) is also present then a small amount of enzyme is produced (Lac repressor is not bound to the operator).
* When glucose is absent, CAP-cAMP binds to a specific DNA site upstream of the promoter and makes a direct protein-protein interaction with RNAP that facilitates the binding of RNAP to the promoter.
The delay between growth phases reflects the time needed to produce sufficient quantities of lactose-metabolizing enzymes. First, the CAP regulatory protein has to assemble on the lac promoter, resulting in an increase in the production of lac mRNA. More available copies of the lac mRNA results in the production (see translation) of significantly more copies of LacZ (β-galactosidase, for lactose metabolism) and LacY (lactose permease to transport lactose into the cell). After a delay needed to increase the level of the lactose metabolizing enzymes, the bacteria enter into a new rapid phase of cell growth.
Two puzzles of catabolite repression relate to how cAMP levels are coupled to the presence of glucose, and secondly, why the cells should even bother. After lactose is cleaved it actually forms glucose and galactose (easily converted to glucose). In metabolic terms, lactose is just as good a carbon and energy source as glucose. The cAMP level is related not to intracellular glucose concentration but to the rate of glucose transport, which influences the activity of adenylate cyclase. (In addition, glucose transport also leads to direct inhibition of the lactose permease.) As to why E. coli works this way, one can only speculate. All enteric bacteria ferment glucose, which suggests they encounter it frequently. It is possible that a small difference in efficiency of transport or metabolism of glucose v. lactose makes it advantageous for cells to regulate the lac operon in this way. | 1 | Applied and Interdisciplinary Chemistry |
Promoters of active genes have nucleosome free regions (NFR). This allows for promoter DNA accessibility to various proteins, such as transcription factors. Nucleosome free region typically spans for 200 nucleotides in S. cerevisiae Well-positioned nucleosomes form boundaries of NFR. These nucleosomes are called +1-nucleosome and −1-nucleosome and are located at canonical distances downstream and upstream, respectively, from transcription start site. +1-nucleosome and several downstream nucleosomes also tend to incorporate H2A.Z histone variant. | 1 | Applied and Interdisciplinary Chemistry |
The olfactory receptor neuron has a fast working negative feedback response upon depolarization. When the neuron is depolarizing, the CNG ion channel is open allowing sodium and calcium to rush into the cell. The influx of calcium begins a cascade of events within the cell. Calcium first binds to calmodulin to form CaM. CaM will then bind to the CNG channel and close it, stopping the sodium and calcium influx. CaMKII will be activated by the presence of CaM, which will phosphorylate ACIII and reduce cAMP production. CaMKII will also activate phosphodiesterase, which will then hydrolyze cAMP. The effect of this negative feedback response inhibits the neuron from further activation when another odor molecule is introduced. | 1 | Applied and Interdisciplinary Chemistry |
Pharmacometabolomics is thought to provide information that complements that gained from other omics, namely genomics, transcriptomics, and proteomics. Looking at the characteristics of an individual down through these different levels of detail, there is an increasingly more accurate prediction of a person's ability to respond to a pharmaceutical compound. The genome, made up of 25 000 genes, can indicate possible errors in drug metabolism; the transcriptome, made up of 85,000 transcripts, can provide information about which genes important in metabolism are being actively transcribed; and the proteome, >10,000,000 members, depicts which proteins are active in the body to carry out these functions. Pharmacometabolomics complements the omics with direct measurement of the products of all of these reactions, but with perhaps a relatively smaller number of members: that was initially projected to be approximately 2200 metabolites, but could be a larger number when gut derived metabolites and xenobiotics are added to the list. Overall, the goal of pharmacometabolomics is to more closely predict or assess the response of an individual to a pharmaceutical compound, permitting continued treatment with the right drug or dosage depending on the variations in their metabolism and ability to respond to treatment.
Pharmacometabolomic analyses, through the use of a metabolomics approach, can provide a comprehensive and detailed metabolic profile or “metabolic fingerprint” for an individual patient. Such metabolic profiles can provide a complete overview of individual metabolite or pathway alterations, providing a more realistic depiction of disease phenotypes. This approach can then be applied to the prediction of response to a pharmaceutical compound by patients with a particular metabolic profile. Pharmacometabolomic analyses of drug response are often coupled or followed up with pharmacogenetics studies. Pharmacogenetics focuses on the identification of genetic variations (e.g. single-nucleotide polymorphisms) within patients that may contribute to altered drug responses and overall outcome of a certain treatment. The results of pharmacometabolomics analyses can act to “inform” or “direct” pharmacogenetic analyses by correlating aberrant metabolite concentrations or metabolic pathways to potential alterations at the genetic level. This concept has been established with two seminal publications from studies of antidepressants serotonin reuptake inhibitors where metabolic signatures were able to define pathway implicated in response to the antidepressant and that lead to identification of genetic variants within a key gene within highlighted pathway as being implicated in variation in response. These genetic variants were not identified through genetic analysis alone and hence illustrated how metabolomics can guide and inform genetic data. | 1 | Applied and Interdisciplinary Chemistry |
Not just one but multiple mitogenic mutations are required for cancer to proliferate. Generally, multiple mutations in different subsystems (an oncogene and a tumor suppressor gene) are the most effective at causing cancer. For example, a mutation that hyperactivates the oncogene Ras and another that inactivates the tumor suppressor pRb is far more tumorigenic than either protein alone.
Tumor cells are also resistant to the hyperproliferation stress response. Normal cells have apoptotic proteins that will respond to an overstimulation of mitogenic signaling pathways by triggering cell death or senescence. This generally prevents the onset of cancer from a single oncogenic mutation. In tumor cells, there is generally another mutation that inhibits apoptotic proteins as well, suppressing the hyperproliferation stress response. | 1 | Applied and Interdisciplinary Chemistry |
Alkene carboamination is the simultaneous formation of C–N and C–C bonds across an alkene. This method represents a powerful strategy to build molecular complexity with up to two stereocenters in a single operation. Generally, there are four categories of reaction modes for alkene carboamination. The first class is cyclization reactions, which will form a N-heterocycle as a result. The second class has been well established in the last decade. Alkene substrates with a tethered nitrogen nucleophile have been used in these transformations to promote intramolecular aminocyclization. While intermolecular carboamination is extremely hard, people have developed a strategy to combine the nitrogen and carbon part, which is known as the third class. The most general carboamination, which takes three individual parts and couples them together is still underdeveloped. | 0 | Theoretical and Fundamental Chemistry |
Hypophosphorous acid was first prepared in 1816 by the French chemist Pierre Louis Dulong (1785–1838).
The acid is prepared industrially via a two step process: Firstly, elemental white phosphorus reacts with alkali and alkaline earth hydroxides to give an aqueous solution of hypophosphites:
:P + 4 OH + 4 HO → 4 + 2 H
Any phosphites produced in this step can be selectively precipitated out by treatment with calcium salts. The purified material is then treated with a strong, non-oxidizing acid (often sulfuric acid) to give the free hypophosphorous acid:
: + H → HPO
HPA is usually supplied as a 50% aqueous solution. Anhydrous acid cannot be obtained by simple evaporation of the water, as the acid readily oxidises to phosphorous acid and phosphoric acid and also disproportionates to phosphorous acid and phosphine. Pure anhydrous hypophosphorous acid can be formed by the continuous extraction of aqueous solutions with diethyl ether. | 0 | Theoretical and Fundamental Chemistry |
Increasing levels of nitrogen deposition are shown to have a number of negative effects on both terrestrial and aquatic ecosystems. Nitrogen gases and aerosols can be directly toxic to certain plant species, affecting the aboveground physiology and growth of plants near large point sources of nitrogen pollution. Changes to plant species may also occur, as accumulation of nitrogen compounds increase its availability in a given ecosystem, eventually changing the species composition, plant diversity, and nitrogen cycling. Ammonia and ammonium – two reduced forms of nitrogen – can be detrimental over time due to an increased toxicity toward sensitive species of plants, particularly those that are accustomed to using nitrate as their source of nitrogen, causing poor development of their roots and shoots. Increased nitrogen deposition also leads to soil acidification, which increases base cation leaching in the soil and amounts of aluminum and other potentially toxic metals, along with decreasing the amount of nitrification occurring and increasing plant-derived litter. Due to the ongoing changes caused by high nitrogen deposition, an environment's susceptibility to ecological stress and disturbance – such as pests and pathogens – may increase, thus making it less resilient to situations that otherwise would have little impact to its long-term vitality.
Additional risks posed by increased availability of inorganic nitrogen in aquatic ecosystems include water acidification; eutrophication of fresh and saltwater systems; and toxicity issues for animals, including humans. Eutrophication often leads to lower dissolved oxygen levels in the water column, including hypoxic and anoxic conditions, which can cause death of aquatic fauna. Relatively sessile benthos, or bottom-dwelling creatures, are particularly vulnerable because of their lack of mobility, though large fish kills are not uncommon. Oceanic dead zones near the mouth of the Mississippi in the Gulf of Mexico are a well-known example of algal bloom-induced hypoxia. The New York Adirondack Lakes, Catskills, Hudson Highlands, Rensselaer Plateau and parts of Long Island display the impact of nitric acid rain deposition, resulting in the killing of fish and many other aquatic species.
Ammonia () is highly toxic to fish and the level of ammonia discharged from wastewater treatment facilities must be closely monitored. To prevent fish deaths, nitrification via aeration prior to discharge is often desirable. Land application can be an attractive alternative to the aeration. | 1 | Applied and Interdisciplinary Chemistry |
The IL-10 family is one of the important types of cytokines, that can stop the inflammation. In general. these cytokines have a helical structure of homodimers. The difference that the members of IL-10 family have between each other is that they have various receptor-binding residues, which help with interaction with specific cytokine receptors. The features of the IL-10 family consists of their genomic structure being similar, their primary and secondary protein structures being similar, their a clustering of encoding genes, and their utilization the similar receptor complexes. | 1 | Applied and Interdisciplinary Chemistry |
A 4n + 2 electrocyclic ring opening reaction is also a 2-component pericyclic reaction which is suprafacial with respect to the π-system. Thus, in order for the reaction to be allowed, the number of antarafacial components must be 0, i.e. it must be suprafacial with respect to the breaking σ-bond as well. Thus a disrotatory mechanism is symmetry-allowed. | 0 | Theoretical and Fundamental Chemistry |
The only stable yttrium isotope, Y, will be found with yield somewhat less than 1% in a fission product mixture which has been allowed to age for months or years, as the next-longest lived yttrium isotopes have half-lives of only 107 days (Y) or 59 days (Y). However, a small amount of yttrium-90 will be found in secular equilibrium with its parent strontium-90 unless the two elements are separated from each other.
Sr decays into Y which is a beta emitter with a half-life of 2.67 days.
Y is sometimes used for medical purposes and can be obtained either by the neutron activation of stable Y or by using a device similar to a technetium cow.
As the half lives of the unstable Yttrium isotopes are low ( being the longest at 106 days), yttrium extracted from strontium-free moderately aged spent fuel has negligible radioactivity. However, the strong gamma emitter will be present as long as its parent nuclide is. Should a nonradioactive sample of Yttrium be desired, care must be taken to remove all traces of strontium and sufficient time to let the short lived Y-90 (64 hours half life) decay must be allowed before the product can be used. | 0 | Theoretical and Fundamental Chemistry |
Once the autocorrelation data have been generated, different mathematical approaches can be employed to obtain information from it. Analysis of the scattering is facilitated when particles do not interact through collisions or electrostatic forces between ions. Particle-particle collisions can be suppressed by dilution, and charge effects are reduced by the use of salts to collapse the electrical double layer.
The simplest approach is to treat the first-order autocorrelation function as a single exponential decay. This is appropriate for a monodisperse population.
where is the decay rate. The translational diffusion coefficient may be derived at a single angle or at a range of angles depending on the wave vector .
with
where is the incident laser wavelength, is the solvent refractive index and is the angle at which the detector is located with respect to the sample cell.
The refractive index of the solvent plays a crucial role in light scattering and is important to calculate the Stokes radius from the Stokes-Einstein equation. Therefore, previous refractive index data from the scattering medium should be evaluated with dedicated instruments, known as refractometers. Alternatively, DLS instruments containing a refractive index measurement module allow a good estimative for this important parameter within ±0.5%, which is the accuracy defined by ISO 22412:2017 for refractive index values required for DLS. Besides the refractive index of the medium, the refractive index of the particles is only necessary when analyzing larger particle size (usually above 100 nm) and volume- or number-weighted size distributions are needed. In these cases, prior knowledge of the refractive index and absorbance of the material is required in order to apply the Mie scattering.
Depending on the anisotropy and polydispersity of the system, a resulting plot of vs. may or may not show an angular dependence. Small spherical particles will show no angular dependence, hence no anisotropy. A plot of vs. will result in a horizontal line. Particles with a shape other than a sphere will show anisotropy and thus an angular dependence when plotting vs. . The intercept will be in any case the D. Thus, there is an optimum angle of detection for each particle size. A high-quality analysis should always be performed at several scattering angles (multiangle DLS). This becomes even more important in a polydisperse sample with an unknown particle size distribution. At certain angles the scattering intensity of some particles will completely overwhelm the weak scattering signal of other particles, thus making them invisible to the data analysis at this angle. DLS instruments which only work at a fixed angle can only deliver good results for some particles. Thus, the indicated precision of a DLS instrument with only one detection angle is only ever true for certain particles.
is often used to calculate the hydrodynamic radius of a sphere through the Stokes–Einstein equation. It is important to note that the size determined by dynamic light scattering is the size of a sphere that moves in the same manner as the scatterer. So, for example, if the scatterer is a random coil polymer, the determined size is not the same as the radius of gyration determined by static light scattering. It is also useful to point out that the obtained size will include any other molecules or solvent molecules that move with the particle. So, for example, colloidal gold with a layer of surfactant will appear larger by dynamic light scattering (which includes the surfactant layer) than by transmission electron microscopy (which does not "see" the layer due to poor contrast).
In most cases, samples are polydisperse. Thus, the autocorrelation function is a sum of the exponential decays corresponding to each of the species in the population.
It is tempting to obtain data for and attempt to invert the above to extract . Since is proportional to the relative scattering from each species, it contains information on the distribution of sizes. However, this is known as an ill-posed problem. The methods described below (and others) have been developed to extract as much useful information as possible from an autocorrelation function. | 0 | Theoretical and Fundamental Chemistry |
In 1884, in association with Dr. Ernst Abbe and Carl Zeiss, Otto founded Glastechnische Laboratorium Schott & Genossen (Schott & Associates Glass Technology Laboratory) in Jena. It was here, during the period 1887 through to 1893, that Schott developed borosilicate glass. Borosilicate glass is distinguished for its high tolerance to heat and a substantial resistance to thermal shock resulting from sudden temperature changes and resistance to degradation when exposed to corrosive chemicals. This type of glass initially became known under the brand name Duran. Their business enterprise also commercialized apochromatic lenses that had low chromatic aberration and was based on Schott's systematic investigations of the composition and properties of glass.
Schott used borosilicate glass to make laboratory and medical supplies, including thermometers, glassware for laboratory use, medicine vials and pharmaceutical tubing. Schott produced domestic glassware under the brandname "Jenaer Glas". He also produced heat resistant lamp cylinders for use in gas lighting. Carl Auers incandescent gas lamps were first sold in 1894 and became a lucrative source of income for Schotts glassworks. In late 1890s he was also involved in the electrification of the industry in Jena. Schott's business enterprise held a near monopoly on global optical glass from its inception until the start of World War I.
In 1919, Schott & Associates became wholly owned by the Carl Zeiss Foundation, although Schott & Associates is known in the early 21st century as Schott AG. The Schott Company's brand became associated with high quality and specialty optics.
As of 2020, vials made of glass from Schott AG were being used in vaccination efforts against COVID-19 disease. | 0 | Theoretical and Fundamental Chemistry |
Pdr1p (Pleiotropic Drug Resistance 1p) is a transcription factor found in yeast and is a key regulator of genes involved in general drug response. It induces the expression of ATP-binding cassette transporter, which can export toxic substances out of the cell, allowing cells to survive under general toxic chemicals. It binds to DNA sequences that contain certain motifs called pleiotropic drug response element (PDRE). Pdr1p is encoded by a gene called PDR1 (also known as YGL013C) on chromosome VII. | 1 | Applied and Interdisciplinary Chemistry |
Pharmacogenetics has become a controversial issue in the area of bioethics. Privacy and confidentiality are major concerns. The evidence of benefit or risk from a genetic test may only be suggestive, which could cause dilemmas for providers. Drug development may be affected, with rare genetic variants possibly receiving less research. Access and patient autonomy are also open to discussion. | 1 | Applied and Interdisciplinary Chemistry |
A common example is NMR. In this process, the nuclear spin of an atom starts rotating, with the frequency of rotation proportional to the external magnetic field that the atom experiences. However, in an inhomogeneous medium, the magnetic field often varies from point to point (depending, for example, on the magnetic susceptibility of nearby atoms), so the frequency of nuclear spin rotation is different in different places. Therefore, when detecting the resonant rotation frequency, there is a linewidth (i.e., finite range of different frequencies) due to the variation in that resonant frequency from point to point. (This is called "inhomogeneous broadening".)
However, if the atoms are diffusing around the system, they will experience a higher magnetic field than average sometimes, and a lower magnetic field than average other times. Therefore, (in accordance with the central limit theorem), the time-averaged magnetic field experienced by an atom has less variation than the instantaneous magnetic field does. As a consequence, when detecting the resonant rotation frequency, the linewidth is smaller (narrower) than it would be if the atoms were stationary. This is the motional narrowing effect. | 0 | Theoretical and Fundamental Chemistry |
The traditional technique of titanium production is via the Kroll process which involves chlorination of TiO ore in the presence of carbon and reacting the resulting TiCl with magnesium to produce titanium sponge. These processes take place at temperatures as high as 1040 °C. The sponge particle range in size from 45 to 180 μm, with particles ~150 μm termed sponge fines. These fines are irregularly shaped and porous with a sponge-like morphology. The fines are then blended with alloy additions; cold compacted into a green compact at up to 415 MPa then vacuum sintered at 1260 °C to produce a 99.5% dense component. Hot isostatic pressing (HIP) can further increase the density of these parts and produce components more economically than cast or wrought parts, but the porosity present in the material degrades fatigue and fracture properties. The BE approach has been used to produce valves for the Toyota Altezza, golf club heads and softball bats. More recently, close to 100% dense Ti Grade 5 parts has been achieved using a hydrided powder along with 60:40 Al:V master alloy. The mechanical properties compare well with those exhibited by cast-and-wrought products. A cost estimate of less than $3.00 for a 0.320 g automotive connection link has been made. | 1 | Applied and Interdisciplinary Chemistry |
PMCA has been applied to replicate the misfolded protein from diverse species. The newly generated protein exhibits the same biochemical, biological, and structural properties as brain-derived PrP and strikingly it is infectious to wild type animals, producing a disease with similar characteristics as the illness produced by brain-isolated prions. | 1 | Applied and Interdisciplinary Chemistry |
Thermophotonics (often abbreviated as TPX) is a concept for generating usable power from heat which shares some features of thermophotovoltaic (TPV) power generation. Thermophotonics was first publicly proposed by solar photovoltaic researcher Martin Green in 2000. However, no TPX device is known to have been demonstrated to date, apparently because of the stringent requirement on the emitter efficiency.
A TPX system consists of a light-emitting diode (LED) (though other types of emitters are conceivable), a photovoltaic (PV) cell, an optical coupling between the two, and an electronic control circuit. The LED is heated to a temperature higher than the PV temperature by an external heat source. If no power is applied to the LED, the system functions much like a very inefficient TPV system, but if a forward bias is applied at some fraction of the bandgap potential, an increased number of electron-hole pairs (EHPs) will be thermally excited to the bandgap energy. These EHPs can then recombine radiatively so that the LED emits light at a rate higher than the thermal radiation rate ("superthermal" emission). This light is then delivered to the cooler PV cell over the optical coupling and converted to electricity.
The control circuit presents a load to the PV cell (presumably at the maximum power point) and converts this voltage to a voltage level that can be used to sustain the bias of the emitter. Provided that the conversion efficiencies of electricity to light and light to electricity are sufficiently high, the power harnessed from the PV cell can exceed the power going into the bias circuit, and this small fraction of excess power (originating from the heat difference) can be utilized. It is thus in some sense a photonic heat engine.
Possible applications of thermophotonic generators include solar thermal electricity generation and utilization of waste heat. TPX systems may have the potential to generate power with useful levels of output at temperatures where only thermoelectric systems are now practical, but with higher efficiency.
A patent application for a thermophotonic generator using a vacuum gap with thickness on the order of a micrometer or less was published by the US Patent Office in 2009 and assigned to MTPV Corporation of Austin, Texas, USA. This proposed variant of the technology allows better thermal insulation because of the gap between the hot emitter and cold receiver, while maintaining relatively good optical coupling between them due to the gap's being small relative to the optical wavelength. | 0 | Theoretical and Fundamental Chemistry |
The electrical conductivity of a solution of an electrolyte is measured by determining the resistance of the solution between two flat or cylindrical electrodes separated by a fixed distance. An alternating voltage is generally used in order to minimize water electrolysis. The resistance is measured by a conductivity meter. Typical frequencies used are in the range 1–3 kHz. The dependence on the frequency is usually small, but may become appreciable at very high frequencies, an effect known as the Debye–Falkenhagen effect.
A wide variety of instrumentation is commercially available. Most commonly, two types of electrode sensors are used, electrode-based sensors and inductive sensors. Electrode sensors with a static design are suitable for low and moderate conductivities, and exist in various types, having either two or four electrodes, where electrodes can be arrange oppositely, flat or in a cylinder. Electrode cells with a flexible design, where the distance between two oppositely arranged electrodes can be varied, offer high accuracy and can also be used for the measurement of highly conductive media. Inductive sensors are suitable for harsh chemical conditions but require larger sample volumes than electrode sensors. Conductivity sensors are typically calibrated with KCl solutions of known conductivity. Electrolytic conductivity is highly temperature dependent but many commercial systems offer automatic temperature correction.
Tables of reference conductivities are available for many common solutions. | 0 | Theoretical and Fundamental Chemistry |
Snieckus' research interests in organic synthesis focused on metalation and particularly lithiation. He is best known for his work on the directed ortho metalation family of reactions. His work has had practical applications in both academic and industrial settings, particularly in the industrial-scale synthesis of pharmaceuticals and in an agricultural antifungal. | 0 | Theoretical and Fundamental Chemistry |
Coordination complexes have been known since the beginning of modern chemistry. Early well-known coordination complexes include dyes such as Prussian blue. Their properties were first well understood in the late 1800s, following the 1869 work of Christian Wilhelm Blomstrand. Blomstrand developed what has come to be known as the complex ion chain theory. In considering metal amine complexes, he theorized that the ammonia molecules compensated for the charge of the ion by forming chains of the type [(NH)], where X is the coordination number of the metal ion. He compared his theoretical ammonia chains to hydrocarbons of the form (CH).
Following this theory, Danish scientist Sophus Mads Jørgensen made improvements to it. In his version of the theory, Jørgensen claimed that when a molecule dissociates in a solution there were two possible outcomes: the ions would bind via the ammonia chains Blomstrand had described or the ions would bind directly to the metal.
It was not until 1893 that the most widely accepted version of the theory today was published by Alfred Werner. Werner's work included two important changes to the Blomstrand theory. The first was that Werner described the two possibilities in terms of location in the coordination sphere. He claimed that if the ions were to form a chain, this would occur outside of the coordination sphere while the ions that bound directly to the metal would do so within the coordination sphere. In one of his most important discoveries however Werner disproved the majority of the chain theory. Werner discovered the spatial arrangements of the ligands that were involved in the formation of the complex hexacoordinate cobalt. His theory allows one to understand the difference between a coordinated ligand and a charge balancing ion in a compound, for example the chloride ion in the cobaltammine chlorides and to explain many of the previously inexplicable isomers.
In 1911, Werner first resolved the coordination complex hexol into optical isomers, overthrowing the theory that only carbon compounds could possess chirality. | 0 | Theoretical and Fundamental Chemistry |
Herbicides can be classified/grouped in various ways; for example, according to their activity, the timing of application, method of application, mechanism of their action, and their chemical structures. | 1 | Applied and Interdisciplinary Chemistry |
This article relates primarily to RPMs deployed for screening trucks at ports of entry. Over 1400 RPMs are deployed at US borders and a similar number at foreign locations for the purpose of interdicting illicit radiological and nuclear material. The US deployments cover all land border vehicles, all seaport containerized cargo, and all mail and express courier facilities. Efforts are also being made to deploy similar measures to other cross border vectors including:
* Pedestrian radiation portal monitoring
* Air freight radiation portal monitoring
* Crane based radiation portal monitoring
* Air luggage radiation portal monitoring
* Railway radiation portal monitoring
RPMs are also deployed at civilian and military nuclear facilities to prevent theft of radiological materials. Steel mills often use RPMs to screen incoming scrap metal to avoid radioactive sources illegally disposed in this way. Garbage incineration plants often monitor incoming material to avoid contamination. | 0 | Theoretical and Fundamental Chemistry |
His contribution to food science was celebrated in a special edition of the Journal of Texture Studies He also initiated what he called psycho-rheology: the effect of food texture on the consumer. However he promoted and was a major contributor to the study of the rheological effects in blood flow to the genitalia, as well as biological systems in general. The journal Biorheology, which he co-founded, published an obituary. His contribution to medical science was recognised in his obituary in the journal Thrombosis Research. | 0 | Theoretical and Fundamental Chemistry |
Ocean salinity is derived mainly from the weathering of rocks and the transport of dissolved salts from the land, with lesser contributions from hydrothermal vents in the seafloor. Evaporation of ocean water and formation of sea ice further increase the salinity of the ocean. However these processes which increase salinity are continually counterbalanced by processes that decrease salinity, such as the continuous input of fresh water from rivers, precipitation of rain and snow, and the melting of ice. The two most prevalent ions in seawater are chloride and sodium. Together, they make up around 85 per cent of all dissolved ions in the ocean. Magnesium and sulfate ions make up most of the rest. Salinity varies with temperature, evaporation, and precipitation. It is generally low at the equator and poles, and high at mid-latitudes. | 0 | Theoretical and Fundamental Chemistry |
In nuclear science, the decay chain refers to a series of radioactive decays of different radioactive decay products as a sequential series of transformations. It is also known as a "radioactive cascade". The typical radioisotope does not decay directly to a stable state, but rather it decays to another radioisotope. Thus there is usually a series of decays until the atom has become a stable isotope, meaning that the nucleus of the atom has reached a stable state.
Decay stages are referred to by their relationship to previous or subsequent stages. A parent isotope is one that undergoes decay to form a daughter isotope. One example of this is uranium (atomic number 92) decaying into thorium (atomic number 90). The daughter isotope may be stable or it may decay to form a daughter isotope of its own. The daughter of a daughter isotope is sometimes called a granddaughter isotope. Note that the parent isotope becomes the daughter isotope, unlike in the case of a biological parent and daughter.
The time it takes for a single parent atom to decay to an atom of its daughter isotope can vary widely, not only between different parent-daughter pairs, but also randomly between identical pairings of parent and daughter isotopes. The decay of each single atom occurs spontaneously, and the decay of an initial population of identical atoms over time t, follows a decaying exponential distribution, e, where λ is called a decay constant. One of the properties of an isotope is its half-life, the time by which half of an initial number of identical parent radioisotopes can be expected statistically to have decayed to their daughters, which is inversely related to λ. Half-lives have been determined in laboratories for many radioisotopes (or radionuclides). These can range from nearly instantaneous (less than 10 seconds) to more than 10 years.
The intermediate stages each emit the same amount of radioactivity as the original radioisotope (i.e., there is a one-to-one relationship between the numbers of decays in successive stages) but each stage releases a different quantity of energy. If and when equilibrium is achieved, each successive daughter isotope is present in direct proportion to its half-life; but since its activity is inversely proportional to its half-life, each nuclide in the decay chain contributes as many individual transformations as the head of the chain, though not the same energy. For example, uranium-238 is weakly radioactive, but pitchblende, a uranium ore, is 13 times more radioactive than the pure uranium metal because of the presence of shorter-lived decay products, such as radium and the noble gas radon. Rock containing thorium and/or uranium (such as some types of granite) emits radon gas, which tends to accumulate in enclosed places such as basements or underground mines due to its high density.
The quantity of isotopes in the decay chains at a certain time are calculated with the Bateman equation. | 0 | Theoretical and Fundamental Chemistry |
The first proponents of ecosan systems had a strong focus on increasing agricultural productivity (via the reuse of excreta as fertilizers) and thus improving the nutritional status of the people at the same time as providing them with safe sanitation. Disease reduction was meant to be achieved not only by reducing infections transmitted via the fecal–oral route but also by reducing malnutrition in children. This link between WASH, nutrition, a disease called environmental enteropathy (or tropical enteropathy) as well as stunted growth of children has risen to the top of the agenda of the WASH sector since about 2013.
Agricultural trials around the world have shown measurable benefits of using treated excreta in agriculture as a fertilizer and soil conditioner. This applies in particular to the use of urine. Reuse trials in Zimbabwe showed positive results for using urine on green, leafy plants such as spinach or maize as well as fruit trees. Another study in Finland indicated that the use of urine and the use of urine and wood ash "could produce 27% and 10% more red beet root biomass". Urine has been proven in many studies to be a valuable, relatively easy to handle fertilizer, containing nitrogen, phosphorus, potassium and important micro-nutrients. | 1 | Applied and Interdisciplinary Chemistry |
Wood permeable pavement is a natural and sustainable building material. Architects and landscape designers turning towards permeable pavers will find that some types of highly durable hardwoods (e.g. Black Locust) are an effective permeable pavers material. Wood paver blocks made of Black Locust provide a highly permeable, durable surface that will last for decades because of the characteristics of the wood. Black Locust Lumber wood pavers exceed 10.180 PSI (pounds per square inch) and have a Janka Hardness 1,700 lbf. They are suitable for pedestrian and vehicular traffic in the form of pathways and driveways and are placed upon permeable foundations. | 1 | Applied and Interdisciplinary Chemistry |
Resource recovery from fecal sludge can take many forms, including as a fuel, soil amendment, building material, protein, animal fodder, and water for irrigation. Some of the by-products from fecal sludge treatment processes have the potential to offset some of the costs of collection and treatment, thereby reducing tariffs for the households. However, value addition all the way to biogas, biodiesel and electricity is difficult to achieve in practice due to technological and operational challenges. | 1 | Applied and Interdisciplinary Chemistry |
The modern non-stick pans were made using a coating of Teflon (polytetrafluoroethylene or PTFE). PTFE was invented serendipitously by Roy Plunkett in 1938, while working for a joint venture of the DuPont company. The substance was found to have several unique properties, including very good corrosion-resistance and the lowest coefficient of friction of any substance yet manufactured. PTFE was first used to make seals resistant to the uranium hexafluoride gas used in development of the atomic bomb during World War II, and was regarded as a military secret. Dupont registered the Teflon trademark in 1944 and soon began planning for post-war commercial use of the new product.
By 1951 Dupont had developed applications for Teflon in commercial bread and cookie-making; however, the company avoided the market for consumer cookware due to potential problems associated with release of toxic gases if stove-top pans were overheated in inadequately ventilated spaces. While working at DuPont, NYU Tandon School of Engineering alumnus John Gilbert was asked to evaluate a newly developed material called Teflon. His experiments using the fluorinated polymer as a surface coating for pots and pans helped usher in a revolution in non-stick cookware.
A few years later, a French engineer had begun coating his fishing gear with Teflon to prevent tangles. His wife Colette suggested using the same method to coat her cooking pans. The idea was successful and a French patent was granted for the process in 1954. The Tefal company was formed in 1956 to manufacture non-stick pans. | 0 | Theoretical and Fundamental Chemistry |
*1991 National Science Foundation Faculty Award for Women Scientists
*1994 Alexander von Humboldt Foundation Max Planck Research Award
*1996 American Physical Society Fellow
*2005 American Physical Society Herbert P. Broida Prize
*2006 National Science Foundation CAREER Award
*2007 University of Southern California Remarkable Women Award
*2010 University of Southern California Provost's Mentoring Award
*2012 American Association for the Advancement of Science Fellow | 0 | Theoretical and Fundamental Chemistry |
Surface runoff is defined as precipitation (rain, snow, sleet, or hail) that reaches a surface stream without ever passing below the soil surface. It is distinct from direct runoff, which is runoff that reaches surface streams immediately after rainfall or melting snowfall and excludes runoff generated by the melting of snowpack or glaciers.
Snow and glacier melt occur only in areas cold enough for these to form permanently. Typically snowmelt will peak in the spring and glacier melt in the summer, leading to pronounced flow maxima in rivers affected by them. The determining factor of the rate of melting of snow or glaciers is both air temperature and the duration of sunlight. In high mountain regions, streams frequently rise on sunny days and fall on cloudy ones for this reason.
In areas where there is no snow, runoff will come from rainfall. However, not all rainfall will produce runoff because storage from soils can absorb light showers. On the extremely ancient soils of Australia and Southern Africa, proteoid roots with their extremely dense networks of root hairs can absorb so much rainwater as to prevent runoff even with substantial amounts of rainfall. In these regions, even on less infertile cracking clay soils, high amounts of rainfall and potential evaporation are needed to generate any surface runoff, leading to specialised adaptations to extremely variable (usually ephemeral) streams. | 1 | Applied and Interdisciplinary Chemistry |
Overheating is a phenomenon of rising temperatures in an electrical circuit. Overheating causes damage to the circuit components and can cause fire, explosion, and injury. Damage caused by overheating is usually irreversible; the only way to repair it is to replace some components. | 0 | Theoretical and Fundamental Chemistry |
Research has been conducted to explore the possibility of developing a heterologous SARS-CoV receptor-binding domain (RBD) recombinant protein as a human vaccine against COVID-19. The theory is supported by evidence that convalescent serum from SARS-CoV patients have the ability to neutralise SARS-CoV-2 (corresponding virus for COVID-19) and that amino acid similarity between SARS-CoV and SARS-CoV-2 spike and RBD protein is high (82%). | 1 | Applied and Interdisciplinary Chemistry |
The perovskite structure is adopted at high pressure by bridgmanite, a silicate with the chemical formula , which is the most common mineral in the Earth's mantle. As pressure increases, the SiO tetrahedral units in the dominant silica-bearing minerals become unstable compared with SiO octahedral units. At the pressure and temperature conditions of the lower mantle, the second most abundant material is likely the rocksalt-structured oxide, periclase.
At the high pressure conditions of the Earths lower mantle, the pyroxene enstatite, MgSiO, transforms into a denser perovskite-structured polymorph; this phase may be the most common mineral in the Earth. This phase has the orthorhombically distorted perovskite structure (GdFeO-type structure) that is stable at pressures from ~24 GPa to ~110 GPa. However, it cannot be transported from depths of several hundred km to the Earths surface without transforming back into less dense materials. At higher pressures, MgSiO perovskite, commonly known as silicate perovskite, transforms to post-perovskite. | 0 | Theoretical and Fundamental Chemistry |
Sawdust (or wood dust) is a by-product or waste product of woodworking operations such as sawing, sanding, milling and routing. It is composed of very small chips of wood. These operations can be performed by woodworking machinery, portable power tools or by use of hand tools. In some manufacturing industries it can be a significant fire hazard and source of occupational dust exposure.
Sawdust, as particulates, is the main component of particleboard. Research on health hazards comes from the field of occupational safety and health, and study of ventilation happens in indoor air quality engineering. Sawdust is an IARC group 1 Carcinogen. | 1 | Applied and Interdisciplinary Chemistry |
The wide variety of electrophilic aminating reagents precludes generalization of reaction conditions. Electrophilic nitrogen sources are, however, either toxic or explosive in general. Great care should be taken while handling these reagents. Many electrophilic nitrogen sources do not provide amines immediately, but a number of methods exist to generate the corresponding amines.
* Tosylamines: tributyltin hydride
* Azo compounds: H/Pd
* Triazenes: sodium borohydride
* Azides: H/Pd, H/Pt, lithium aluminum hydride, triphenylphosphine
Conversion to other nitrogen-containing functionality, including enamines, imines, and amides, is also possible. | 0 | Theoretical and Fundamental Chemistry |
Atropisomers are stereoisomers resulting from hindered rotation about single bonds where the steric strain barrier to rotation is high enough to allow for the isolation of the conformers. | 0 | Theoretical and Fundamental Chemistry |
1,2-Indandione is an organic compound with the molecular formula CH(CO)CH. A yellow solid, it is classified as a vicinal diketone on an indane framework.
1,2-Indandione is used in the first stage of forensic identification of latent fingerprints. It is particularly useful for paper, and for items printed with thermal inks such as receipts. Amino acids left behind by the human hand may be developed into fingerprints by the use of it; the results, photographed with a special filter under a strong yellow-green fluorescent or green laser. It is usually the first method employed in a sequential analysis aimed at the production of evidence of a grade suitable for use in the courtroom.
1,2-Indanedione is prepared by oxidation of 1-indanone with selenium dioxide. | 0 | Theoretical and Fundamental Chemistry |
Several fluorescent protein exist in nature, but the most important one as a research tool is Green Fluorescent Protein (GFP) from the jellyfish Aequorea victoria, which spontaneously fluoresces upon folding via specific serine-tyrosine-glycine residues. The benefit that GFP and other fluorescent proteins have over organic dyes or quantum dots is that they can be expressed exogenously in cells alone or as a fusion protein, a protein that is created by ligating the fluorescent gene (e.g., GFP) to another gene and whose expression is driven by a housekeeping gene promoter or another specific promoter. This approach allows fluorescent proteins to be used as reporters for any number of biological events, such as sub-cellular localization and expression patterns.
A variant of GFP is naturally found in corals, specifically the Anthozoa, and several mutants have been created to span the visible spectra and fluoresce longer and more stably.
Other proteins are fluorescent but require a fluorophore cofactor, and hence can only be used in vitro; these are often found in plants and algae (phytofluors, phycobiliprotein such as allophycocyanin). | 1 | Applied and Interdisciplinary Chemistry |
plants often possess a characteristic leaf anatomy called kranz anatomy, from the German word for wreath. Their vascular bundles are surrounded by two rings of cells; the inner ring, called bundle sheath cells, contains starch-rich chloroplasts lacking grana, which differ from those in mesophyll cells present as the outer ring. Hence, the chloroplasts are called dimorphic. The primary function of kranz anatomy is to provide a site in which can be concentrated around RuBisCO, thereby avoiding photorespiration. Mesophyll and bundle sheath cells are connected through numerous cytoplasmic sleeves called plasmodesmata whose permeability at leaf level is called bundle sheath conductance. A layer of suberin is often deposed at the level of the middle lamella (tangential interface between mesophyll and bundle sheath) in order to reduce the apoplastic diffusion of (called leakage). The carbon concentration mechanism in plants distinguishes their isotopic signature from other photosynthetic organisms.
Although most plants exhibit kranz anatomy, there are, however, a few species that operate a limited cycle without any distinct bundle sheath tissue. Suaeda aralocaspica, Bienertia cycloptera, Bienertia sinuspersici and Bienertia kavirense (all chenopods) are terrestrial plants that inhabit dry, salty depressions in the deserts of the Middle East. These plants have been shown to operate single-cell -concentrating mechanisms, which are unique among the known mechanisms. Although the cytology of both genera differs slightly, the basic principle is that fluid-filled vacuoles are employed to divide the cell into two separate areas. Carboxylation enzymes in the cytosol are separated from decarboxylase enzymes and RuBisCO in the chloroplasts. A diffusive barrier is between the chloroplasts (which contain RuBisCO) and the cytosol. This enables a bundle-sheath-type area and a mesophyll-type area to be established within a single cell. Although this does allow a limited cycle to operate, it is relatively inefficient. Much leakage of from around RuBisCO occurs.
There is also evidence of inducible photosynthesis by non-kranz aquatic macrophyte Hydrilla verticillata under warm conditions, although the mechanism by which leakage from around RuBisCO is minimised is currently uncertain. | 0 | Theoretical and Fundamental Chemistry |
* R: (:ja:理科年表): An (mostly) annual reference book published in Japan since 1925CE. Note that the actual published year is typically one year earlier than the nominal (book title) year.
</references>
* I: : Revised roughly by each decade. First edition 1935CE.
</references>
*D: Kyoritsu Great Dictionary of Chemistry
</references>
*X: Other usage examples
</references> | 0 | Theoretical and Fundamental Chemistry |
Award programs highlight copper architecture installations in Canada and the U.S. and in Europe. An International Copper and the Home Competition also exists. Judged by architecture and copper industry experts, criteria for the awards programs include copper in building design, craft of copper installation, excellence in innovation, and historic renovation. | 1 | Applied and Interdisciplinary Chemistry |
By oral route, phenethylamine's half-life is minutes; endogenously produced PEA in catecholamine neurons has a half-life of roughly 30 seconds. In humans, PEA is metabolized by phenylethanolamine N-methyltransferase (PNMT), monoamine oxidase A (), monoamine oxidase B (), the semicarbazide-sensitive amine oxidases (SSAOs) AOC2 and AOC3, flavin-containing monooxygenase 3 (FMO3), and aralkylamine N-acetyltransferase (AANAT). , an isomer of amphetamine, is produced in humans via the metabolism of phenethylamine by PNMT. β-Phenylacetic acid is the primary urinary metabolite of phenethylamine and is produced via monoamine oxidase metabolism and subsequent aldehyde dehydrogenase metabolism. Phenylacetaldehyde is the intermediate product which is produced by monoamine oxidase and then further metabolized into β-phenylacetic acid by aldehyde dehydrogenase.
When the initial phenylethylamine concentration in the brain is low, brain levels can be increased when taking a monoamine oxidase inhibitor (MAOI), particularly a MAO-B inhibitor, and by times when the initial concentration is high. | 1 | Applied and Interdisciplinary Chemistry |
In bipolar disorder, repurposed drugs are emerging as feasible augmentation options. Several agents, all sustained by a plausible biological rationale, have been evaluated. Evidence from meta-analyses showed that adjunctive allopurinol and tamoxifen were superior to placebo for mania, and add-on modafinil/armodafinil and pramipexole seemed to be effective for bipolar depression, while the efficacy of celecoxib and N-acetylcysteine appeared to be limited to certain outcomes.
Further, meta-analytic evidence exists also for adjunctive melatonin and ramelteon in mania, and for add-on acetylsalicylic acid, pioglitazone, memantine, and inositol in bipolar depression, but findings were not significant.
The generally low quality of evidence does not allow making reliable recommendations for the use of repurposed drugs in clinical practice, but some of these drugs have shown promising results and deserve further attention in research. | 1 | Applied and Interdisciplinary Chemistry |
is a biweekly peer-reviewed scientific journal published by Elsevier. It was established in 1950 and is sponsored by the Geochemical Society and the Meteoritical Society. The editor-in-chief is Jeffrey Catalano (Washington University in St. Louis). The journal covers topics in Earth geochemistry, planetary geochemistry, cosmochemistry and meteoritics.
Publishing formats include original research articles and invited reviews and occasional editorials, book reviews, and announcements. In addition, the journal publishes short comments (4 pages) targeting specific articles and designed to improve understanding of the target article by advocating a different interpretation supported by the literature, followed by a response by the author. | 0 | Theoretical and Fundamental Chemistry |
All data in HMDB is non-proprietary or is derived from a non-proprietary source. It is freely accessible and available to anyone. In addition, nearly every data item is fully traceable and explicitly referenced to the original source. HMDB data is available through a public web interface and downloads. | 1 | Applied and Interdisciplinary Chemistry |
In 1821, the German physicist Thomas Johann Seebeck discovered that a magnetic needle held near a circuit made up of two dissimilar metals got deflected when one of the dissimilar metal junctions was heated. At the time, Seebeck referred to this consequence as thermo-magnetism. The magnetic field he observed was later shown to be due to thermo-electric current. In practical use, the voltage generated at a single junction of two different types of wire is what is of interest as this can be used to measure temperature at very high and low temperatures. The magnitude of the voltage depends on the types of wire being used. Generally, the voltage is in the microvolt range and care must be taken to obtain a usable measurement. Although very little current flows, power can be generated by a single thermocouple junction. Power generation using multiple thermocouples, as in a thermopile, is common.
The standard configuration for thermocouple usage is shown in the figure.
Briefly, the desired temperature T is obtained using three inputs—the characteristic function E(T) of the thermocouple, the measured voltage V, and the reference junctions temperature T'.
The solution to the equation E(T) = V + E(T) yields T.
These details are often hidden from the user since the reference junction block (with T thermometer), voltmeter, and equation solver are combined into a single product. | 1 | Applied and Interdisciplinary Chemistry |
The Annual Review of Physical Chemistry published its first volume in 1950. Its founding editor was University of California chemist Gerhard Krohn Rollefson. Some branches of physical chemistry were designated to be reviewed with each volume, while other branches would be reviewed less frequently. Upon Rollefsons death in 1955, he was succeeded by Henry Eyring. The editorial committee considered changing the name of the journal in the 1980s to the Annual Review of Physical Chemistry and Chemical Physics', though decided against it by 1988. In addition to publishing reviews about physical chemistry, many volumes contain a prefatory chapter with an informal review of a chemist or institution. As of 2020, it was published both in print and electronically.
It defines its scope as covering recent developments in the fields of biophysical chemistry, chemical kinetics, colloids, electrochemistry, geochemistry, cosmochemistry, atmospheric chemistry, laser chemistry and ultrafast processes, the liquid state, magnetic resonance, physical organic chemistry, polymers, and macromolecules. As of 2023, Journal Citation Reports gives it a 2022 impact factor of 14.7, ranking it sixteenth of 161 journal titles in the category "Physical Chemistry". | 0 | Theoretical and Fundamental Chemistry |
One set of Woodward–Fieser rules for dienes is outlined in table 1. A diene is either homoannular with both double bonds contained in one ring or heteroannular with two double bonds distributed between two rings.
With the aid of these rules the UV absorption maximum can be predicted, for example in these two compounds:
In the compound on the left, the base value is 214 nm (a heteroannular diene). This diene group has 4 alkyl substituents (labeled 1,2,3,4) and the double bond in one ring is exocyclic to the other (adding 5 nm for an exocyclic double bond). In the compound on the right, the diene is homoannular with 4 alkyl substituents. Both double bonds in the central B ring are exocyclic with respect to rings A and C.
For polyenes having more than 4 conjugated double bonds one must use Fieser–Kuhn rules. | 0 | Theoretical and Fundamental Chemistry |
Lisinopril is contraindicated in people who have a history of angioedema (hereditary or idiopathic) or who have diabetes and are taking aliskiren. | 0 | Theoretical and Fundamental Chemistry |
Dynamic kinetic resolution has also been applied to the total synthesis of a variety of natural products. After Bäckvall's discoveries in 2007, he employed another enzyme-metal coupled reaction to synthesize the natural product (R)-Bufuralol.
The key step that the literature points out utilizes DKR to convert the chlorohydrin into the (S)-acetate by means of a lipase and a ruthenium catalyst.
The lipase PS-C “Amano” II has been reported in the literature to be particularly enantioselective for the 1-phenyl-2-chloroethanol motif. The enzyme, along with the ruthenium catalyst, allows for rapid racemization of the chlorohydrin with a selective binding to the (S) isomer for the acetylation reaction. Here isopropenyl acetate is used as the acyl donor. The product is achieved in excellent yield (96%) and near-perfect enantiomeric excess (>99%). | 0 | Theoretical and Fundamental Chemistry |
STAT4 is involved in several autoimmune and cancer diseases in animal models humans, significantly in the disease progression and pathology. STAT4 were significantly increased in patients with colitis ulcerative and skin T cells of psoriatic patients. Moreover, STAT4 -/- mice developed less severe experimental autoimmune encephalo-myelitis (EAE) than the wild type mice.
Intronic single nucleotide polymorphism (SNP) mostly in third intron of the STAT4 has shown to be associated with immune dysregulation and autoimmunity including systemic lupus erythematosus (SLE) and rheumatoid arthritis as well as Sjögren's disease (SD), systemic sclerosis, psoriasis and also type-1 diabetes. High incident of STAT4 genetic polymorphisms and susceptibility to autoimmune diseases is a reason to consider the STAT4 as general autoimmune disease susceptibility locus. | 1 | Applied and Interdisciplinary Chemistry |
Favre averaging is carried out for all dynamical variables except the pressure. For the velocity components, , the Favre averaging is defined as
where the overbar indicates the typical Reynolds averaging, the tilde denotes the Favre averaging and is the density field. The Favre decomposition of the velocity components is then written as
where is the fluctuating part in the Favre averaging, which satisfies the condition , that is to say, . The normal Reynolds decomposition is given by , where is the fluctuating part in the Reynolds averaging, which satisfies the condition . The Favre-averaged variables are more difficult to measure experimentally than the Reynolds-averaged ones, however, the two variables can be related in an exact manner if correlations between density and the fluctuating quantity is known; this is so because, we can write
The advantage of Favre-averaged variables are clearly seen by taking the normal averaging of the term that appears in the convective term of the Navier-Stokes equations written in its conserved form. This is given by
As we can see, there are five terms in the averaging when expressed in terms of Reynolds-averaged variables, whereas we have only two terms when it is expressed in terms of Favre-averaged variables. | 1 | Applied and Interdisciplinary Chemistry |
Trichloroethylene is metabolised to trichloroepoxyethane (TCE oxide) which rapidly isomerises to trichloroacetaldehyde (chloral). Chloral hydrates to chloral hydrate in the body. Chloral hydrate is either reduced to 2,2,2-trichloroethanol or oxidised to trichloroacetic acid. Monochloroacetic acid, dichloroacetic acid and trichloromethane were also detected as minor metabolites of TCE. | 1 | Applied and Interdisciplinary Chemistry |
To assess pharmacological cardiotoxicity, it was common practice to measure QT interval in vivo and the blockage of potassium channel. Nevertheless, a new paradigm has been developed to overcome the limits of the previous one since 2013. In fact, it has been demonstrated that the old paradigm was stringent, labeling as pro-arrhythmic some pharmacological compounds which actually were not. | 1 | Applied and Interdisciplinary Chemistry |
Iron–nickel (Fe–Ni) clusters are metal clusters consisting of iron and nickel, i.e. Fe–Ni structures displaying polyhedral frameworks held together by two or more metal–metal bonds per metal atom, where the metal atoms are located at the vertices of closed, triangulated polyhedra.
Individually, iron (Fe) and nickel (Ni) generally form metal clusters with π-acceptor ligands. Π acceptor ligands are ligands that remove some of the electron density from the metal.
Figure 1 contains pictures of representative cluster shapes. Clusters take the form of closed, triangulated polyhedral.
Corresponding bulk systems of Fe and Ni atoms show a variety of composition-dependent abnormalities and unusual effects. Fe–Ni composites are studied in hopes to understand and utilize these unusual and new properties.
Fe–Ni clusters are used for several main purposes. Fe–Ni clusters ranging from single to hundreds of atoms are used in catalysis, depending on the reaction mechanism. Additionally, Fe–Ni clusters, usually of one or two metal atoms, are used in biological systems. These applications are discussed below. | 0 | Theoretical and Fundamental Chemistry |
Fatty acids are broken down to acetyl-CoA by means of beta oxidation inside the mitochondria, whereas fatty acids are synthesized from acetyl-CoA outside the mitochondria, in the cytosol. The two pathways are distinct, not only in where they occur, but also in the reactions that occur, and the substrates that are used. The two pathways are mutually inhibitory, preventing the acetyl-CoA produced by beta-oxidation from entering the synthetic pathway via the acetyl-CoA carboxylase reaction. It can also not be converted to pyruvate as the pyruvate dehydrogenase complex reaction is irreversible. Instead the acetyl-CoA produced by the beta-oxidation of fatty acids condenses with oxaloacetate, to enter the citric acid cycle. During each turn of the cycle, two carbon atoms leave the cycle as CO in the decarboxylation reactions catalyzed by isocitrate dehydrogenase and alpha-ketoglutarate dehydrogenase. Thus each turn of the citric acid cycle oxidizes an acetyl-CoA unit while regenerating the oxaloacetate molecule with which the acetyl-CoA had originally combined to form citric acid. The decarboxylation reactions occur before malate is formed in the cycle. Only plants possess the enzymes to convert acetyl-CoA into oxaloacetate from which malate can be formed to ultimately be converted to glucose.
However, acetyl-CoA can be converted to acetoacetate, which can decarboxylate to acetone (either spontaneously, or catalyzed by acetoacetate decarboxylase). It can then be further metabolized to isopropanol which is excreted in breath/urine, or by CYP2E1 into hydroxyacetone (acetol). Acetol can be converted to propylene glycol. This converts to pyruvate (by two alternative enzymes), or propionaldehyde, or to -lactaldehyde then -lactate (the common lactate isomer). Another pathway turns acetol to methylglyoxal, then to pyruvate, or to -lactaldehyde (via -lactoyl-glutathione or otherwise) then -lactate. D-lactate metabolism (to glucose) is slow or impaired in humans, so most of the D-lactate is excreted in the urine; thus -lactate derived from acetone can contribute significantly to the metabolic acidosis associated with ketosis or isopropanol intoxication. -Lactate can complete the net conversion of fatty acids into glucose. The first experiment to show conversion of acetone to glucose was carried out in 1951. This, and further experiments used carbon isotopic labelling. Up to 11% of the glucose can be derived from acetone during starvation in humans.
The glycerol released into the blood during the lipolysis of triglycerides in adipose tissue can only be taken up by the liver. Here it is converted into glycerol 3-phosphate by the action of glycerol kinase which hydrolyzes one molecule of ATP per glycerol molecule which is phosphorylated. Glycerol 3-phosphate is then oxidized to dihydroxyacetone phosphate, which is, in turn, converted into glyceraldehyde 3-phosphate by the enzyme triose phosphate isomerase. From here the three carbon atoms of the original glycerol can be oxidized via glycolysis, or converted to glucose via gluconeogenesis. | 1 | Applied and Interdisciplinary Chemistry |
In May 1940, Hansgirg left Japan for the United States after the political mood became "hostile to foreigners". In the United States, Hansgirg joined forces with American industrialist Henry J. Kaiser. Before the war, the demand for aircraft engineering had increased the need for light magnesium alloys. Kaiser had paid $750,000 to Winter for the patent in the carbothermic process and received government credits of about $22 million to build a plant for Permanente Metals Corporation (PMC) in California By 1941, the first unit at Kaiser's plant was producing about of magnesium per day.
However, getting the Permanete plant working was dangerous and fraught with problems. The technology for the Hansgirg process was still as unreliable as it had been in Radenthein, as it required handling magnesium dust which ignites explosively in air. PMC engineers built a pilot plant to improve the process. However, instead of modifying the approach, PMC chemists found a new use for the magnesium dust. They invented a new incendiary mixture of "goop" – a paste of magnesium dust gelled with gasoline and additives, which could be used as a bomb. Government controls allowed PMC to price the "goop" in competition with napalm, and avoid large financial losses. By September 1943, only 10% of the dust was being used to produce magnesium as ingots. For the entire war period, PMC issued 20 million lbs. of magnesium and 86 million lbs. of "goop". The proportion of incendiary bombs with "goop" constituted about 8% of the total tonnage of incendiary devices used in the bombing of Japan and Germany. After the war, the Permanente plant was halted, and at the end of 1945 Kaiser repaid his credits.
Nine days after the December 7, 1941, attack on Pearl Harbour plunged the United States into World War II, Hansgirg was arrested by the FBI on a presidential warrant accused of being "potentially dangerous to the public peace and safety of the United States".
After arrest, Hansgirg was first held in jail in Santa Clara County, California, and later at U.S. alien internment camps in San Antonio, Texas and Stringtown, Oklahoma.
During Hansgirgs wartime internment, U.S. attorney general Francis Biddle denied permission for his wife to visit him. Heller appealed in a hand-written woman-to-woman' letter to First Lady Eleanor Roosevelt seeking leniency, explaining that her husband could not criticize Adolf Hitler because their son was still in the German army and would be retaliated against if he did so. She ended this letter by stating: | 0 | Theoretical and Fundamental Chemistry |
A biogenic substance is a product made by or of life forms. While the term originally was specific to metabolite compounds that had toxic effects on other organisms, it has developed to encompass any constituents, secretions, and metabolites of plants or animals. In context of molecular biology, biogenic substances are referred to as biomolecules. They are generally isolated and measured through the use of chromatography and mass spectrometry techniques. Additionally, the transformation and exchange of biogenic substances can by modelled in the environment, particularly their transport in waterways.
The observation and measurement of biogenic substances is notably important in the fields of geology and biochemistry. A large proportion of isoprenoids and fatty acids in geological sediments are derived from plants and chlorophyll, and can be found in samples extending back to the Precambrian. These biogenic substances are capable of withstanding the diagenesis process in sediment, but may also be transformed into other materials. This makes them useful as biomarkers for geologists to verify the age, origin and degradation processes of different rocks.
Biogenic substances have been studied as part of marine biochemistry since the 1960s, which has involved investigating their production, transport, and transformation in the water, and how they may be used in industrial applications. A large fraction of biogenic compounds in the marine environment are produced by micro and macro algae, including cyanobacteria. Due to their antimicrobial properties they are currently the subject of research in both industrial projects, such as for anti-fouling paints, or in medicine. | 0 | Theoretical and Fundamental Chemistry |
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